Contoured crushable composite structural members and methods for making the same

ABSTRACT

The present invention provides contoured crushable composite structural members and methods for making the same. The contoured structural members comprise composite materials sandwiching a support or stabilizing structure. The contoured structure can be provided by tube rolling (or roll wrapping) the composite materials and the support structure together and then, if necessary, bonding them or connecting them. The structural members are made crushable by incorporating an initiator into the structures of the members. With a contoured, crushable, and generally non-flat structure, applications for the structural members of the present invention are nearly limitless.

REFERENCES TO RELATED APPLICATIONS

This application claims priority from U.S. provisional patentapplication No. 60/216,636, Jul. 7, 2000 the entire disclosure of whichis incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to structural members and methods formaking the same. In particular, the present invention relates to coredcomposite crushable contoured parts and methods for making the same.

BACKGROUND OF THE INVENTION

In recent years there has been an increasing emphasis on the use oflightweight composite materials. One application, for example, has beentheir use to improve the efficiency of motor vehicles. To that end, theUnited States Government and the U.S. Council for Automotive Research(USCAR)—which represents Daimler Chrysler, Ford, and General Motors havepartnered to form the Partnership for a New Generation of Vehicles(PNGV). One goal of PNGV is to develop technology, such as compositetechnology, that can be used to create environmentally friendly vehicleswith up to triple the fuel efficiency, while providing today'saffordability, performance and safety. For example, PNGV wants toimprove the fuel efficiency of today's vehicles from about 28 miles pergallon (mpg) to about 83 mpg and a 40-60% decrease in the present curbweight (3200 pounds).

One method to improve the fuel efficiency is to decrease the weight oftoday's vehicles and use lighter weight materials. The materials used intoday's vehicles, such as steel and aluminum, are quite heavy relativeto composite materials, but have been necessary to provide sufficientstructural properties, including tensile, compression, flexural,interlaminar shear, and in-plane shear strengths and other mechanicaland material properties, to meet vehicle design requirements.

Many other applications of lightweight composites have been made tosupplement or replace the use of structural materials, such as steel,cast iron, and aluminum. These include buildings, bridges, recreationalvehicles, aerospace, defense, and sporting goods, as well as many otherapplications.

Composites are a mixture or combination, on a macro scale, of two ormore materials that are solid in the finished state, are mutuallyinsoluble, and differ in chemical nature. Types of composites includelaminar, particle, fiber, flake, and filled composites. Composites,however, often have not had the combination of structural propertiesmentioned above and/or low cost necessary to promote their wide-spreaduse in motor vehicle and other applications.

Despite their lack of structural strength, some composite materials havebeen employed in vehicle manufacturing. For example, laminated compositetubes above have been used as structural members in vehicles to reducethe weight and increase the energy absorbing characteristics. Typically,the tube is generally straight over its length and resists axial impactsat the end of the tube by absorbing the energy of the axial impact andcrushing at that location. Known means for energy absorption by crushingin composite tubes, include knife-edges, slits, bevels and plugs, andthe like at the end of the tube as described in U.S. Pat. Nos.4,742,899, 5,732,801, and 5,914,163, the disclosures of which areincorporated herein by reference. The crushing characteristics, however,of such composite materials are still fairly limited when compared tomore traditional structural materials. For example, such energyabsorption means do not exhibit the desired progressive crush beginningat any selected location other than the end of the tube.

One way to increase the structural properties of composite materials,particularly the torsional or flexural strength, is to make them in amore structurally efficient form. In one more structurally efficientform, composite materials have been combined with a supportingstructure, such as a honeycomb or foam structure, by sandwiching thesupporting structure between panels of the composite material. Examplesof such combinations have been described in U.S. Pat. Nos. 5,006,391,5,195,779, 5,652,039, 5,834,082, 5,848,767, 5,849,122, and 5,875,609,the disclosures of which are incorporated herein by reference. Suchcombinations, however, have been generally limited to relatively flatstructures and so the use of such materials have been quite limited.

SUMMARY OF THE INVENTION

The present invention provides contoured crushable composite structuralmembers and methods for making the same. The contoured structuralmembers comprise composite materials sandwiching a support orstabilizing structure. The contoured structure can be provided by tuberolling (or roll wrapping) the composite materials and the supportstructure together and then, if necessary, bonding them or connectingthem. With a contoured, crushable, and generally non-flat structure,applications for the structural members of the present invention arenearly limitless. The structural members are made crushable byincorporating an initiator into the structural members. The structuralmember crushes at the location of the initiator by absorbing the energyof an exerting load.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-15 are views of structural members and methods of making thesame according to the present invention. FIGS. 1-15 presented inconjunction with this description are views of only particular—ratherthan complete—portions of the structural members and methods of makingthe same.

DETAILED DESCRIPTION OF THE INVENTION

The following description provides specific details in order to providea thorough understanding of the present invention. The skilled artisan,however, would understand that the present invention can be practicedwithout employing these specific details. Indeed, the present inventioncan be practiced by modifying the illustrated structural member andmethod and can be used in conjunction with apparatus and techniquesconventionally used in the industry.

FIG. 1 illustrates one contoured structural member—a tubular member witha substantially circular cross-section—according to the presentinvention. In the context of the present invention, a “contoured”structural member is any shape, size, or configuration where at leastone portion of the outer or inner periphery of such member issubstantially non-flat, including curved, geometric or irregular.Preferably, the contoured structural members have a closed surfaceconfiguration, such as a surface which facilitates their manufacture asexplained below. In the context of the present invention, a “closed”structural member is one having any shape, size, or configuration whereat least one portion of the surface (inner and/or outer) of such memberis a substantially closed or substantially continuous. Examples of aclosed configuration include a tubular, substantially spherical,polygonal, conical, or other similar shape, as well as those illustratedand described herein.

The structural members of the present invention may have a cylindricalor a non-cylindrical configuration such as cones, pyramid, pods,hemispheres or spheres. The structural members of the present inventionmay also have a circular or a non-circular cross-section such asrectangular, square, hexagonal, octagonal, or the like. They may alsocomprise very irregular, non-closed, substantially planar surfaces.Indeed, the structural members of the present invention could have anycomplex contoured shape or combination of contoured shapes. Thestructural members of the present invention are characterized by thefact that they are substantially non-flat and thereby distinguished fromknown sheet-like cored composite structures.

In FIG. 1, tubular structural member 2 comprises inner section orportion 4, intermediate section or portion 6, outer section or portion8, and optional core region 10. Inner portion 4, outer portion 8, andoptional core region 10, can be made of any suitable composite materialas described below. Intermediate portion 6 is a “cored” structure thatboth attaches to and supports and/or stabilizes the inner and outerportions.

Core region 10 is located in an inner section of structural member 2and, as described below, is about the size of the substrate or mandrelused in forming the structural member. Core region 10 can be of anysuitable size, shape, or configuration depending primarily on theremovable mandrel(s) in the manufacturing process used to makestructural member 2, the configuration of structural member 2, and thedesired end application of structural member 2.

Core region 10 may be hollow, but may optionally be partially orcompletely filled with any desired core material such as foam, plastic,conducting or insulating materials, metals and/or the like. Core region10 containing the core material may be a structural element. The corematerial may also be added after structural member 2 is formed, orformed integrally into the structure. If the core material is addedafter the formation of structural member 2, it may be attached tostructural member 2 using an adhesive or other suitable bonding meansknown in the art.

The materials for inner section 4 and outer section 8 can be the same ordifferent materials. Preferably, inner portion 4 and outer portion 8comprise the same material. In one aspect of the invention, thematerials for the inner or outer portions comprise any suitablereinforced resin matrix material (RRMM), which is a resin matrixmaterial (RMM) with continuous or discontinuous reinforcement materialembedded in the resin matrix. In one aspect of the invention, the RMM isa organic resin matrix material (ORMM). See, for example, U.S. Pat. Nos.5,725,920 and 5,309,620, the disclosures of which are incorporatedherein by reference.

In one aspect of the invention, the ORMM can be a thermoset resin.Thermoset resins are polymeric materials which set irreversibly whenheated. Examples of thermoset resins include epoxy, bismeleimide,polyester, phenolic, polyimide, melamine, xylene, urethane, phenolic,furan, silicone, vinyl ester, and alkyd resins, or combinations thereof.The thermoset resins can contain various additives as known in the art,such as cross-linking agents, curing agents, fillers, binders, orultraviolet inhibitors. Preferably, epoxy, vinyl ester, or polyesterresins are employed as the thermoset resin in the present invention.

In another aspect of the invention, the ORMM can be a thermoplasticresin matrix material. Thermoplastic resins are polymeric materialswhich do not set irreversibly when heated, e.g., they soften whenexposed to heat and then return to their original condition when cooled.Examples of thermoplastic resins include polypropylene, polyethelene,polyamides (nylons), polyesters (PET, PBT), polyether ketone (PEK),polyether ether ketone(PEEK), polyphenylene sulfide (PPS), polyphenyleneoxide (PPO) and its alloys, and polyvinyl resins, or combinationsthereof. The thermoplastic resins can contain various additives as knownin the art, such as cross-linking agents, curing agents, fillers,binders, or ultraviolet inhibitors. Preferably, polyamides (nylons),polyester, polycarbonate and polypropylene resins are employed as thethermoplastic resin in the present invention.

The material used to reinforce the RMM of the present invention can bein any form which reinforces the resin matrix. Examples of reinforcementforms include unidirectional tape, multidirectional tapes, wovenfabrics, roving fabrics, matt fabrics, preforms, fibers, filaments,whiskers, and combinations thereof. The type of material used toreinforce the RMM can be any type serving such a reinforcing function.Preferably, the form of the reinforcement materials for the resin matrixis a fiberous material, such as continuous or discontinuous fibers.Examples of materials that can be employed in the present inventioninclude glass-s, glass-e, aramid, graphite, carbon, ultra-high molecularweight polyethylene, boron, silicon carbide, ceramic, quartz, metals,isotropic metals (aluminum, magnesium and titanium), metal coatedorganic fibers, CAMP, hybrids of these fibers, or combinations of thesefibers. See, for example, U.S. Pat. No. 6,117,534, the disclosure ofwhich is incorporated herein by reference.

In yet another aspect of the invention, non- or partially-curedcomposite materials are used as the material for the inner and/or outersections. Composites are a mixture or combination, on a macro scale, oftwo or more materials that are solid in the finished state, are mutuallyinsoluble, and differ in chemical nature. Any composites known in theart such as laminar, particle, fiber, flake, and filled composites canbe employed in the invention. The non- or partially-cured compositematerials are a ORMM (thermoset or thermoplastic resin) reinforced witha continuous fiber.

Preferable composite materials used for inner section 4 and outersection 8 include B-stage prepreg materials typically in the form ofsheets or laminates, which can be formed by impregnating a plurality offiber reinforcement tows with a formulated resin. Methods of makingB-stage prepreg sheets and the sheets themselves are well known. See,for example, those sheets described in U.S. Pat. No. 4,495,017, thedisclosure of which is incorporated herein by reference. When cured,prepreg materials are generally stronger and stiffer than metals whileproviding greater resistance to fatigue, chemicals, wear and corrosion.Preferable reinforcement for prepregs include aramids, glass materials,nickel carbide, silicone carbide, ceramic, carbons and ultra-highmolecular weight polyethylene, or a combination thereof. See, forexample, U.S. Pat. Nos. 4,968,545, 5,102,723, 5,499,661, 5,579,609, and5,725,920, the disclosures of which are incorporated herein byreference. Carbon, glass, metals and especially isotropic metals likealuminum, magnesium and titanium, metal-coated organic fibers, andaramid fibers, or a combination thereof, can also be employed as thefibers. See, for example, U.S. Pat. Nos. 5,601,892 and 5,624,115, thedisclosures of which are incorporated herein by reference. Preferably,carbon fibers, glass fibers, or aramid fibers and more preferably Kevlar29 or 49 fibers are employed in the present invention.

The fiber volume in the prepregs may be varied so as to maximize themechanical, electrical, and thermal properties. See, for example, U.S.Pat. No. 5,848,767, the disclosure of which is incorporated herein byreference. High fiber volume parts are stiffer and, in the case ofthermally conductive fibers, the parts are more thermally conductive.Fiber volumes in the present invention can range from about 5% to about95%, and preferably range from about 50% to about 65%. The fibers of theprepregs may be oriented within the prepreg material in any desireddirection as known in the art, such as about 0 to about 90 degrees,including equal numbers of fibers balanced in opposing directions. See,for example, U.S. Pat. No. 4,946,721, the disclosure of which isincorporated herein by reference.

In yet another aspect of the invention, sheet molding compounds (SMCs)can be used as the materials for the inner or outer portion. SMCs aresheets made up of B-stage thermoset resin reinforced with adiscontinuous fiber. SMCs are fully formulated ORMM compounds havingdiscontinuous fiber reinforcement materials which are typically formedinto sheet, ply, or laminate—without additional preparation. See, forexample, U.S. Pat. No. 6,103,032, the disclosure of which isincorporated herein by reference. The resins that can be used in theSMCs of the present invention include any of the thermoset resins listedabove. Preferably, polyester or vinyl esters or epoxy resins areemployed as the resin in SMCs of the present invention. The fibers thatcan be used in the SMCs of the present invention include any of thoselisted above. Preferably, glass, carbon, or aramid fibers, and morepreferably Kevlar 29 or 49 fibers can be used as the fibers in the SMCs.The fiber volume in the SMC may also be varied so as to maximize themechanical and thermal properties.

With an unsaturated resin system as its base, SMCs incorporate othermaterials for desirable processing and molding characteristics andoptimum physical and mechanical properties, such as mechanical strength,impact resistance, stiffness, and dimensional stability. Theseincorporated materials include polymers, fibers for reinforcement,resins, fillers, initiators to promote polymerization, viscosity agents,lubricants, mold release agents, catalysts, thickeners, pigments,polyethylene powders, flame retardants, ultraviolet absorbing agents,and other additives. Each of the additives can provide importantproperties to the SMC, either during the processing or molding steps orin the finished parts, and can be incorporated in the SMCs of thepresent invention.

In one aspect of the invention, inner section 4 and outer section 8contain at least one layer of such ORMM materials. One layer issufficient to form the respective inner or outer section and provide thedesired structural characteristics for structural member 2. Additionallayers can be added to improve the strength, stiffness, or otherphysical characteristics of structural member 2. It is possible to use asingle layer with fibers having complementary orientations. It ispreferred, however, to use a plurality of layers with complementaryorientations to balance intrinsic stresses in the layers that make upthe sections that result when, as described below, the B-stage materialsare fully cured. To be complementary, the fibers in successive layersshould be symmetric and balanced (e.g., by having the fibers offset fromthe sheet axis by equal and opposite amounts from one layer to another)as shown in FIG. 2. The fibers can also be oriented to meet the designparameters of the component into which they are being incorporated,e.g., to optimize the structural strength against the expected load. Thefibers could be oriented at any suitable angle, including at anglesranging from about 0 to about 90 degrees, including in ±15, ±30, ±45,±60, and ±75 degrees, or as otherwise known in the art. See, forexample, U.S. Pat. Nos. Re. 35,081 and 5,061,583, the disclosures ofwhich are incorporated herein by reference.

The configuration of inner portion 4 and outer portion 8 can vary withinstructural member 2. For example, the materials used for the composite,the fiber orientation, and the curvature, thickness, shape and othercharacteristics of the inner and/or outer portions (4, 8) can differalong the length and width of structural member 2. See, for example,U.S. Pat. No. 5,718,212, the disclosure of which is incorporated byreference.

Intermediate portion 6 of the structural member 2 of the presentinvention has any structure which spaces and/or supports inner portion 4and outer portion 8, as well as enhances the structural properties ofthose two portions when placed therebetween. Further, intermediatesection 6 can be made of any suitable material which separates,supports, stabilizes, couples and attaches inner portion 4 with respectto outer portion 8. Interposing intermediate section 6 between innersection 4 and outer section 8 improves the structural propertiesaccording to well-known principles of engineering mechanics andmechanical engineering of structural member 2 over the properties of amember comprising only appropriately shaped inner section 4 and outersection 8 bonded together. Preferably, as illustrated in FIG. 1, theintermediate portion is substantially contiguous with the outer surfaceof inner section 4 and the inner surface of outer section 8, e.g., theintermediate section 6 contacts the inner section 4 and/or the outersection 8 at discrete points over most—if not all—of their surfaces.

In one aspect of the present invention, intermediate portion 6 has aribbed structure (RS), or a structure where any single member (rib) ofthat structure extends continuously from a location proximate the inner(or outer) portion to a location proximate the outer (or inner) portion.In another aspect of the invention, the RS is a structure where any ribconnects at one end to a location proximate the at least one layer ofthe inner (or outer) portion and the other ends abuts or connects toanother rib. Examples of RSs include corrugated materials, posts,curvilinear materials, honeycomb cores, and the like. These structures,as well as other RSs, are illustrated in FIG. 3.

A RS is advantageous because, for the additional weight added, thestructural properties of the structural member are often substantiallyincreased. The RSs contain both “ribs” and a large volume of voids. The“ribs” of the RS enhance the structural properties of the structuralmember while the voids are provided to minimize the weight of the RS.The respective amounts of ribs and voids present in the RSs used in thepresent invention depend on the configuration of the RS selected, e.g.,which of those illustrated in FIG. 3 is selected. Preferably, the amountof voids should be maximized and the amount of ribs minimized, therebygiving the minimum weight for the maximum strength, provided thenecessary (or desired) structural properties of the RS or the structuralmember is obtained.

The RSs employed in the present invention can be incorporated into thestructural member in any suitable manner. In one aspect of theinvention, the RS can be incorporated as a standalone “rib” extendingfrom the at least one layer of the inner portion to the at least onelayer of the outer portion, such as the configurations illustrated inFIG. 3. In another aspect of the invention, the rib can be connected toa supporting sheet(s) or another rib(s) where the sheet(s) or otherrib(s) itself is connected to the at least one layer of the inner orouter portion.

If desired, additional materials can be incorporated into the ribbedstructure. Examples of additional materials that can be incorporatedinto the RS include be filled with materials other than air, such asresins, foams, insulating materials, or NVH (noise, vibration, orharshness) damping materials, and/or the like.

The RS need not be uniform in the structural member. In one aspect ofthe embodiment, the type of ribs in the RS can vary from location tolocation. Further, multiples types of RSs can be combined in the atleast one layer of the intermediate portion. In another aspect of theinvention, the periodicity and/or thickness of the ribs can be changedin different areas of the at least one layer of the intermediateportion. In another aspect of the invention, the strength and otherphysical properties of the ribs can change from one location to another.

The ribs of the RS can be made of any suitable material which exhibitsthe desired structural properties. Suitable materials include anymaterial known in the art to provide such a function, includingmaterials having individual cells like beads, corrugated materials,thermoplastic molded materials, honeycomb materials, woods (balsas), andfoams such as rigid expanded plastic foams, polymer foams, metalcomponents, flexible metal (i.e., aluminum) foams, or any combination ofthese materials. See, for example, U.S. Pat. Nos. 5,344,038, 4,573,707,5,562,981, 4,128,963, 4,968,545, and 5,894,045, the disclosures of whichare incorporated herein by reference.

A preferred intermediate portion 6 may be formed using honeycombmaterials (also known as honeycomb cores). These materials usuallycomprise a thin sheet (or sheets) of material, such as paper or aluminumfoil, which is formed into a variety of random or geometric cellularconfigurations. See U.S. Pat. No. 5,876,654, the disclosure of which isincorporated herein by reference. Honeycomb cores, which have ageometric cellular configuration, are known to have structuralproperties or characteristics that are superior to most foam or solidcores with a comparable density. Honeycomb cores can be made of variousshapes and types of materials such as aluminum, aramid materials such asKorex®, nylon materials such as Nomex®, plastic, reinforced phenols,carbons, and fiberglass, or a combination thereof. Preferably,honeycombs made of Nomex® are employed as the material for intermediateportion 6.

The material and configuration (width, length, and geometric shape) ofthe cells can be optimized to provide the desired support and/orstabilization to the inner and outer portions. For example, the cellsize can range from about ⅛ to about ¾ inches, and is preferably about3/16 inches.

The cells of the honeycomb cores can be filled with materials other thanair, such as resins, foams, insulating materials, or NVH (noise,vibration, or harshness) damping materials, and/or the like. The type ofmaterial used, the thickness, the cell configuration, and “fill-in”material for intermediate portion 6 can vary along the length ofstructural member 2.

The structural member of the present invention may, if desired, haveadditional layers or portions on the outside of outer portion 8. In oneexample, a layer of metal, insulation, another composite material, orhoneycomb core material may be placed over outer portion 8. Numerousadditional portions or layers, including similar or different compositematerials, could be added in a similar manner. In addition, at least onestructural component, such as a bracket, coupler, cap, or the like couldbe located on the end(s) of structural member 2.

The structural member of the present invention may have anysubstantially non-flat contour or configuration. FIG. 4 illustratesseveral such configurations. The structural members illustrated in FIG.4 differ from the structural member illustrated in FIG. 1 in that thecross-section of the tube is not substantially circular.

Structural member 2 can be made crushable by any manner in the art. Inone aspect of the invention, the structural members are made crushableby including at least one crushing initiator (or initiator) adjacent to(or in) portion 4, portion 6, and/or portion 8. For example, as depictedin FIG. 12, the at least one initiator 14 can be incorporated in outerportion 8. However, the at least one initiator can be incorporated ininner portion 4, intermediate portion 6, and/or outer portion 8, as wellas between these portions.

The initiator controls the location where, when an external load isapplied, structural member 2 begins to deform. Often, the structuralmember resists impacts along its longitudinal axis. By including aninitiator, the structural member of the present invention absorbs theenergy of the load by undergoing a localized crush where the initiatoris located, in modes such as transverse shearing, lamina bending, orlocal buckling like monocell buckling, face wrinkling, or core-shearinstability. Thus, the initiator leads to a localized crush of themember so the structural member does not fail at other places. Byincorporating at initiator, the preferred site of collapse of thestructural member can be selected before the expected load is applied.

Any suitable initiator known in the art can be employed in the presentinvention, including those described in U.S. Pat. Nos. 4,742,889,5,732,801, 5,895,699, and 5,914,163, the disclosures of which areincorporated herein by reference. The initiator can be placed at anylocation of structural member 2 depending on the desired characteristicsincluding the crushing strength and crushing length. Preferably, theinitiator is not located at the ends of structural member 2. Morepreferably, the initiator is placed at least about ½ inch to about 2inches away from any end of structural member 2.

Multiple initiators can be placed along separate portions of member 2 todeform (and therefore crush) several locations. Multiple initiators canalso be placed proximate one another at a single portion of member 2 todeform that selected location. The number of initiators can vary,depending on the desired crushing strength and desired crushing length.

The initiator(s) can be of various shapes, sizes, and configurations,but should be substantially similar to the configuration of portion 4,intermediate portion 6, and/or portion 8. The width of the initiator canvary depending on the expected load, the desired crushing strength, andthe desired crush length. For example, the width can range from about1/16 inches to about 1 inch, and is preferably about ½ inches. The shapeof the initiator can also vary depending on the expected load, thedesired crushing strength, and the desired crush length. Generally, theshape is similar to that portion of structural member 2 into which it isincorporated. Thus, the shape can vary from circular, to rectangular ortriangular, to any polygonal shape.

When multiple initiators are employed, they can be located in anydesired location. In one aspect of the invention, the initiators can beeither staggered or inline. The initiators can be inline, meaning thatmultiple initiators are aligned along the length or diameter of thestructural member. The initiators can also be semi-staggered or fullystaggered. In a semi-staggered position, the initiators are onlypartially aligned along a length or diameter of the structural member,e.g., they have overlapping positions (as illustrated in FIG. 13). In afully staggered position, the initiators are not aligned along thelength or diameter of the structural member, e.g., they have nooverlapping positions (as illustrated in FIG. 14).

Any suitable material can be used for the initiator(s) of the presentinvention. Suitable materials used for the initiator can be any materialwhich causes, as explained below, the respective inner and/or outerportion to deform and do not adhere to the materials used in the inner,intermediate, and/or outer portion. Examples of suitable materialsinclude as teflons, rubber bands, bromated films, release films, rubberfilms, polytetrafluoroethylene (PTFE) tape, teflons, backing papers, ora combination thereof. In one aspect of the invention, bromated(“bromo”) films are preferably employed as the material for theinitiator in the present invention.

Bromo films are brominated PTFE coated fiber glass fabric films. Bromofilms are usually an impermeable layer that does not bond to thecomposite material during the curing process (as described below). Thereare two types of bromo films that can be employed as the initiatormaterial: porous and non-porous. Preferably, a non-porous bromo film isemployed as the initiator material, ensuring that there is an unbondedarea in any desired location that will cause the failure in thatparticular location. Numerous bromo films are commercially available,including “Release Ease 234TFP” sold by Air Tech Advanced MaterialsGroup.

It is believed that the initiator works because of the absence of acontinuous layer in the inner, intermediate, and/or outer portion. Thus,the initiator could also be a gap or discontinuity (such as a stressriser) in the layer(s) of the inner, intermediate, and/or outer portion.The discontinuity could be a singular discontinuity such as a fold orirregularity, or plural discontinuities such as a row or column ofcut-outs having any desired shape and size. For example, as illustratedin FIG. 15, a row of cut-outs can be located in a layer of the innerand/or outer portion, as well as the intermediate portion, so that whenassembled, structural member 2 contains at least one initiator 14. Inaddition, when the impact load is an axial load, the initiator could beany material (or lack thereof) which operates as a local stress riser.

The present invention can be made by any suitable process which providesthe structure of structural member 2. Suitable process for making thecomposite layer(s) include any processes known in the art, such asthermoforming, bladder or resin transfer molding, or inflatable mandrelprocesses, as described in U.S. Pat. Nos. 5,225,016, 5,192,384,5,569,508, 4,365,952, 5,225,016, 5,624,519, 5,567,499, and 5,851,336,the disclosures of which are incorporated herein by reference. Anothersuitable process is a vacuum bagging process, such as described in U.S.Pat. No. 5,848,767, the disclosure of which is incorporated herein byreference. Other suitable processes are a filament winding process orsheet or tube rolling (also known as roll wrapping). See, for example,U.S. Pat. Nos. 5,632,940, 5,437,450, 4,365,952, 5,624,529, 5,755,558,4,885,865, 5,332,606, 5,540,877, 5,840,347, and 5,914,163, thedisclosures of which are incorporated herein by reference.

In the filament winding process, filaments of the desired material aredispersed in a matrix of binder material and wound about any suitablesubstrate, such as a mandrel assembly, with a shape generallycorresponding to the desired shape (core region 10) of structural member2. Any suitable mandrel, including those described in U.S. Pat. Nos.5,795,524, 5,645,668, 5,192,384, 5,780,075, 5,632,940, 5,817,203, and5,914,163, the disclosures of which are incorporated by reference, canbe employed in the present invention. The substrate or mandrel must havesufficient strength, desired shape, and be able to withstand theprocessing conditions for making the structural member. Suitablemandrels include those made of metals like steel and aluminum,polycarbonate, thermoplastic, or RRMM materials. The mandrels may besolid or hollow.

The filaments are wound over the mandrel and are reciprocally displacedrelative to the mandrel along the longitudinal or winding axis of themandrel to build portion 4. Additional portions, structures, or layers,such as additional metal or composite layers, can be added as describedabove or as known in the art.

Preferably, the present invention employs a tube rolling (also known asroll wrapping) process for making the structural member of the presentinvention. One exemplary tube rolling process is illustrated in FIG. 5.The tube rolling process employs discrete sheet(s) (or plies orlaminates) of the desired composite material rather than filaments. Thesheet(s) is interleaved, wrapped, or rolled over a mandrel assembly suchas at least one mandrel 20. If desired, a release film can be applied tothe mandrel prior to rolling any materials thereon. When more than onesheet is employed, the sheets can be stacked as illustrated in FIG.2—prior to or during the rolling process—by hand or by any suitablemechanical apparatus, with the fibers of the composite material orientedin the desired orientation. After forming inner portion 4, the materialcomprising intermediate portion 6 is placed, preferably by wrapping orrolling, on inner portion 4 by any suitable human or mechanicalapparatus. The roll wrapping process is then resumed to apply thematerial of outer portion 8. Further details about roll wrappingprocesses are described in Engineered Materials Handbook, Volume 1:Composites, ASM International, pp. 569-574 (1987), the disclosure ofwhich is incorporated herein by reference. Additional layers ormaterials can be added over outer portion 8, if desired, in a similarmanner or as known in the art.

The layers of the individual portions (inner, intermediate, and outer)can be cut and/or patterned such that when roll wrapped, the ends ofindividual sheet(s) substantially abut when rolled, thereby forming abutt joint 30. Preferably, the butt joint formed by the ends of anysingle sheet is staggered from the butt joint formed by the ends of anadjacent sheet, as illustrated in FIG. 6.

Inner portion 4 and outer portion 8 may be formed using differentmethods. For example, inner portion 4 can be formed by filament windingand outer portion 8 by roll wrapping, or vice versa. In this aspect ofthe invention, inner portion 4 may be fully cured prior to theapplication of intermediate portion 6. Similarly, inner portion 4 andintermediate portion 6 may be applied and cured together prior to theapplication of outer portion 8. Other methods known in the art, such asthose described above, could also be combined with roll wrapping to makethe structural members by performing discrete steps by differentmethods. For example, inner portion 4 could be formed using the filamentwinding process, intermediate portion 6 and outer portion 8 could beformed using the roll wrapping process, and then this intermediatestructure could be constrained using a vacuum bagging process.

If desired, a bonding agent can be placed between successive layers ofportions 4, 6, and/or 8. The bonding agent can be placed on selectedareas only, or in a pattern such as in rows and/or columns, or overentire areas of the layer(s)/portion(s). Any suitable agent which helpsbond the layers and is compatible with all of the processes employed tomake structural member 2 can be employed, including glues, curingagents, adhesive materials, or a combination thereof. See, for example,U.S. Pat. No. 5,635,306, the disclosure of which is incorporated hereinby reference. The bonding agent can be applied by hand or mechanicalapparatus prior to, during, or after the assembly of the respectiveportion on the substrate.

Where portions 4, 6, and 8 are successively layed up in an uncured (e.g.B-stage state), the structure has outer portion 8 overlying intermediateportion 6, which overlies inner portion 4, which overlies the mandrel.If necessary to better bond and connect inner portion 4, intermediateportion 6, and outer portion 8 together, the intermediate structureformed by these portions can be constrained. The intermediate structurecan be constrained by applying a suitable compressive force. This can bedone using any suitable means including compressive dies or molds,vacuum bagging, or by using a suitable constraining means, e.g., byplacing it in a plastic or metal mold, or by applying a suitableshrink-wrap tape(s) 22 or tube made of nylon, silicone, orpolypropylene. During the curing process described below, thecompressive means (e.g., the shrink-wrap tape or tube) applies suitablecompressive force by physical or chemical change so that the materialsof structural member 2 contact each other. When the RMM is used in theinner and/or outer portion of the present invention, the compressiveforce squeezes out excess resin during this curing process. See, forexample, U.S. Pat. Nos. 5,600,912 and 5,698,055, the disclosures ofwhich are incorporated herein by reference.

Moreover, if it is still necessary to better bond and connect thematerials in the intermediate structure, they can undergo a suitablechemical reaction. For example, when inner portion 4 and/or outerportion 8 comprise a curable material (e.g., B-stage epoxy prepreg), theintermediate structure can be cured by any suitable means 24, such as anoven curing by applying heat and/or pressure or using an ultraviolet(u.v.) or microwave curing. The necessary heat and/or pressure depend onthe size of the mandrel assembly and the materials used in structuralmember 2. During the curing process, the shrink-wrap tape or tubeapplies suitable compressive force. When the RMM is used in the innerand/or outer portion of the present invention, the compressive forcesqueezes out excess resin during this curing process.

The above process can be modified for structural members not having asubstantially circular cross-section, including those with outerdiameters having at least one flat area or area where the degree ofcurvature is substantially different from other surfaces of structuralmember 2. Examples of such structural members are illustrated in FIG. 4.As illustrated in FIG. 7, where the outer diameter has at least onerelatively flat area, the shrink-wrap material (and accompanyingcompressive force) applied to the intermediate structure may not beuniform. Thus, bonding and connecting the materials to one another maynot be uniform and, therefore, might impair the integrity of structuralmember 2. To more uniformly bond and connect such materials, at leastone pressure distributor 26 is placed over the relatively flat areas ofouter portion 8 prior to applying the shrink-wrap material. The pressuredistributors “distribute” the applied compressive force more evenly tosuch flat areas, allowing a more uniform compressive force to all areasof the intermediate structure.

Any suitable shape of pressure distributors which evenly distribute theapplied compressive force to the intermediate structure can be employedin the present invention. Exemplary shapes of the pressure distributorsinclude substantially semicircular shapes (which provide a substantiallycircular outer surface) and T-shaped distributors where the flat end ofthe “T” abuts (and matches in size) the flat area of the intermediatestructure and the long-end of the “T” extends outwards. Other shapes andconfigurations, including single components rather than pluralcomponents, could be employed provided they evenly distribute thecompressive force over the flat area(s). For the structural member 2like the one illustrated in FIG. 4, substantially semicircular pressuredistributors 26 are depicted in FIG. 7. The pressure distributors of thepresent invention can be made of any suitable material that willmaintain its shape when subjected to the compressive force, such asaluminum, steel, and silicone. Preferably, aluminum is employed as thematerial for the pressure distributor.

The shrink-wrap material can be placed under and/or over the pressuredistributor(s). The shrink-wrap materials underlying the pressuredistributors pressurize the corners, as well as keeping the pressuredistributors from sticking to the intermediate structure. Theshrink-wrap materials overlying the pressure distributors pressurize theflat areas.

The above process can be also be modified for structural members wherethe inner and outer portion do not have the same shape, such as thosedepicted in FIG. 11. Any suitable process modification whichmanufactures differently-shaped inner and outer portions can be employedin the present invention. The following two modifications to the aboveprocess demonstrate this concept. Other modifications could beenvisioned, even though not demonstrated below.

First, the inner portion can have a substantially circular cross-sectionand the outer portion a non-circular cross-section. In such an instance,and as shown in FIG. 8, the process for making a circular-shapedstructural member is followed as described above. To change the shape ofthe outer portion, a number of pressure distributors are placed over thecircular-shaped outer portion prior to the constraining and curingstages. The number of pressure distributors used corresponds to thenumber of flat sides desired, e.g., four for a square, six for ahexagon, etc . . . The process as noted above is then continued for theconstraining and curing stages. During the constraining and curingprocess, the circular outer shape is changed to flat sides of thedesired polygonal shape by the pressure exerted via the pressuredistributors.

Second, the inner portion can have a substantially polygonal shape (i.e,square) and the outer portion a substantially circular shape. In thisaspect of the invention as depicted in FIG. 9, the process for making asquare-shaped structural member is followed as described above. Tochange the shape of the outer portion, the pressure distributors whichare normally placed over the outer portion prior to the constraining andcuring stages are omitted. Thus, the square-shaped outer portion is justwrapped with the constraining means. The process as noted above is thencontinued for the constraining and curing stages. During theconstraining and curing process, the outer shape is changed to asubstantially circular shape by the pressure exerted via theconstraining means.

When used, the constraining means are then removed from the intermediatestructure. For the plastic or metal mold, the mold is opened andremoved. The shrink-wrap tape or tube may have reacted during the curingprocess to form a thin shell and, if desired, may be removed by hand orby a mechanical apparatus. When used, the pressure distributors are alsoremoved.

In another aspect of the invention, the constraining means can be lefton the outer portion either temporarily or permanently. For example, theshrink-wrap tape could be left on the structural member in the form as athin shell for protection during shipping and then removed later. Inanother example, the shrink-wrap tape could be left on the structuralmember permanently as a protective coating.

Through the constraining and curing processes described above, the innerportion and the outer portion are chemically attached and/or orconnected to the intermediate portion. Preferably, the materials of theinner and outer portion both chemically bond to the material of theintermediate portion, thus forming a substantially permanent physicalbond.

Next, the substrate or mandrel may be removed from structural member 2to form core region 10. The mandrel may be removed by any suitableprocess, including any known in the art which safely removes the mandrelwithout adversely impacting structural member 2, such as those disclosedin U.S. Pat. No. 5,900,194 and 5,306,371, the disclosures of which areincorporated herein by reference. If desired, core region 10 can befilled by any desired material as known in the art.

The mandrel can be either a removable mandrel or an integral mandrel. Aremovable mandrel is a mandrel that, as described above, is used in theroll wrapping process and then removed to create interior 10. Anintegral mandrel is a mandrel which becomes part of structural member 2and is not removed. Thus, the mandrel remains in core region 10 andbecomes a part of structural member 2.

When using an integral mandrel, the structural member 2 and the processfor making that member are modified from the above description. In thisaspect of the present invention, the intermediate portion is providedover the integral mandrel, and then the outer portion is provided overthe intermediate portion. The structural member then follows theprocessing described above, with the exception that the integral mandrelis not removed. Thus, the integral mandrel can serve as the innerportion. If desired, an inner portion could still be included over theintegral mandrel, yielding a structural member with an integral mandrel,an inner portion, an intermediate portion, and an outer portion.

At least one initiator 14 may be included in the present invention byany suitable method, including those known in the art. If only one layeris employed for portion 4, intermediate portion 6, and/or portion 8, theinitiator can be created under, in, or over that single layer. When morethan one layer is employed for such portions, such an initiator(s) can,additionally or alternatively, be included between the layers making upthe respective portion.

For example, when the initiator is a gap or discontinuity in portion 4,intermediate portion 6, and/or portion 8, the desired section of thatportion can be removed or altered. Any gap or discontinuity ispreferably, although not necessarily, formed in the material prior tothe roll wrapping operation. The initiator can consist of rows orcolumns of cutouts of any desired shape and size, as exemplified in FIG.15, in the respective material which have been removed by any suitableprocess known in the art, such as stamping. The desired configurationfor the initiator is selected, the desired location(s) for deformationof the structural member are determined, and the initiator(s) is thenplaced by creating a gap or discontinuity in the respective layer(s) ofportion 4, portion 6, and/or portion 8 either before or after therolling operation.

As another example, when the initiator is similar to that illustrated inFIG. 12, the desired width of the initiator material can placed on theselected locations(s) of portion 4, intermediate portion 6, and/orportion 8. The initiator material could be placed by rolling or wrappingthe initiator material under or on the respective inner, intermediate,and/or outer portion. Alternatively, the initiator material could beplaced in or on the sheet(s) prior to the rolling or wrapping process,e.g., by manufacturing the sheet(s) with the initiator formed therein.The desired material and configuration for the initiator is selected,the desired location(s) for deformation of the structural member aredetermined, and the initiator(s) is then placed under, over, or withinthe layer(s) of portion 4, 6, and/or 8 either before or after therolling operation.

Once formed, the structural members of the present invention can bemodified or cut for any desired use. For example, the structural membersillustrated in FIGS. 5 and 7-9 have been cut in half along its length toprovide two structural members. Likewise, the structural members couldbe cut along its length to provide any number of members with thedesired length(s). Numerous shapes and configurations can be made usingby cutting along any dimension of the structural members, especiallywhen combined with the broadest aspects of the processes of the presentinvention. A few examples of such shapes and configurations are shown inFIG. 10. If desired, at least one structural component such as abracket, fastener, coupler, cap, or the like, could be provided onstructural member 2, for example, on the ends thereof.

Roll wrapping is the preferred method for making the structural membersof the present invention. The other methods described above, however,could be combined with roll wrapping to make the structural members by,in one aspect of the invention, performing discrete steps by differentmethods. For example, inner portion 4 could be formed using the filamentwinding process, the intermediate portion 6 and the outer portion 8could be formed using the roll wrapping process, and then theintermediate structure could be constrained using the vacuum baggingprocess.

The structural member of the present invention has numerous uses such asa tie, torsion-bar, tube, beam, column, cylinder and the like and can beused in numerous industries. Primarily, the structural member can beused whenever a lightweight, strong, cylindrical object is required. Thestructural member of the present invention can be used in theautomotive, transportation, aerospace, and defense industries inapplications such as airplane components, vehicle components such astracks, trains, shipping containers, defense-related applications,recreational applications such as bikes, sail masts, shafts for golfclubs and racquets, or commercial applications such as bridges andbuildings.

The following non-limiting examples illustrate the present invention.

EXAMPLE 1

A hollow, cylindrical structural member with a circular cross sectionwas made according to following process. A thin coat of a releasematerial (Frekote 700NC or Axel EM606SL/SP) was applied to a cylindricalaluminum mandrel with a 2.4 inch outer diameter and a length of 48inches.

Two pair of B-stage prepreg laminate sheets (4 individual sheets)containing anisotropic Kevlar fibers in an epoxy-based resin were cutwith measurements of about 9.29 to about 10.8 inches in width and about44 inches in length. The first pair of individual laminate sheets (withsmaller widths) were then overlaid so the fibers in successive sheetswere symmetric and balanced at angles of ±15 degrees. The air betweenthe stacked sheets was removed by using a roller or other suitabledevice. The pair of the stacked prepreg sheets were then roll wrapped byhand onto the aluminum mandrel.

Then, ½ inch wide strips of a bromo film were measured and cut to alength similar to the outside diameter of the stacked sheets on themandrel, e.g., 12½ inches in length. The strips of bromo film was thenroll wrapped over the prepreg sheets on the mandrel. The strips arelocated such, that when the structural member is cut as described below,the strips are about 2 inches away from any desired end of thestructural member.

Next, a honeycomb Hexcell Nomex® core with hexagonal shaped cells and athickness of about 0.2 inches was measured and cut to dimensions ofabout 13 inches by about 44 inches. This honeycomb core was then rollwrapped by hand on the first pair of stacked prepreg sheets and thestrips of bromo film.

Other ½ inch wide strips of bromo film were measured and cut to a lengthsimilar to the outside diameter of the honeycomb core. These strips thenroll wrapped over the honeycomb core to be aligned with the strips underthe honeycomb core. The second pair of individual laminate sheets (withlarger widths) were then overlaid so the fibers in successive sheetswere symmetric and balanced at angles of ±15 degrees. The air betweenthe stacked sheets was removed by using a roller or other suitabledevice. The second pair of the stacked prepreg sheets were then rollwrapped onto the honeycomb core and strips of bromo film.

Next, the resulting intermediate structure was shrink-wrapped. One layerof polyethylene-based shrink-wrap tape was roll wrapped by ashrink-wrapping machine using gauge number 150 on the resultingstructure. Another layer of nylon-based shrink-wrap tape was then rollwrapped by a shrink-wrapping machine using gauge number 200. Anadditional, outer layer of nylon-based shrink-wrap tape was then rollwrapped by a shrink-wrapping machine using gauge number 200 over thepressure distributors.

After this wrapping process, the final structure was subjected to acuring process at about 250 degrees Fahrenheit for about 120 minutesduring which the shrink-wrap tapes applied compressive pressure to theintermediate structure. After this curing process, the outer shell(formed by the outer shrink-wrap tape during the curing process), thepressure distributors, and the inner shell (formed by the “inner”shrink-wrap tapes during the curing process) were removed by hand with aknife. The mandrel was then removed from the center of the tube by handand the tube was cut to the desired length.

EXAMPLE 2

A hollow, cylindrical structural member with a square-shaped crosssection was made according to following process. A thin coat of arelease material (Frekote 700NC or Axel EM606SL/SP) was applied to acylindrical aluminum mandrel with a 3.0 inch square outer diameter and alength of 72 inches.

Four pairs of B-stage prepreg laminate sheets (8 individual sheets)containing anisotropic Kevlar fibers in an epoxy-based resin were cutwith measurements of about 11.6 to 13.4 inches in width and about 64inches in length. The individual laminate sheets were then overlaid sothe fibers in successive sheets were symmetric and balanced at angles of±15 degrees. The air between the stacked sheets was removed by using aroller or other suitable device. Two pairs of the stacked prepreg sheetswere then roll wrapped by hand onto the aluminum mandrel.

Then, ½ inch wide strips of bromo film were measured and cut to a lengthsimilar to the outside diameter of the stacked sheets on the mandrel,e.g., 12½ inches in length. The strips were then roll wrapped over theprepreg sheets on the mandrel. The strips are located such, that whenthe structural member is cut as described below, the strips are about 2inches away from any desired end of the structural member.

Next, a honeycomb Hexcell Nomex® core with hexagonal shaped cells and athickness of about 0.2 inches was measured and cut to dimensions ofabout 13 inches by about 64 inches. This honeycomb core was then rollwrapped by hand on the first set of stacked prepreg sheets and strips ofbromo film.

Additional ½ inch wide strips of bromo film were measured and cut to alength similar to the outside diameter of the honeycomb core. The stripsthen roll wrapped over the honeycomb core to be aligned with the stripsunder the core. The other two pairs of the stacked prepreg sheets werethen roll wrapped onto the honeycomb core and the strips of bromo film.

Next, the resulting intermediate structure was shrink-wrapped. One layerof polyethylene-based shrink-wrap tape was roll wrapped by ashrink-wrapping machine using gauge number 150 on the resultingstructure. Another layer of nylon-based shrink-wrap tape was then rollwrapped by a shrink-wrapping machine using gauge number 200. Four 4-inch“T”-shaped pressure distributors made of aluminum were placed on thefour sides of the resulting device. An additional, outer layer ofnylon-based shrink-wrap tape was then roll wrapped by a shrink-wrappingmachine using gauge number 200 over the pressure distributors.

After this wrapping process, the final structure was subjected to acuring process at about 250 degrees Fahrenheit for about 120 minutesduring which the shrink-wrap tapes applied compressive pressure to theintermediate structure. After this curing process, the outer shell(formed by the outer shrink-wrap tape during the curing process), thepressure distributors, and the inner shell (formed by the “inner”shrink-wrap tapes during the curing process) were removed by hand with aknife. The mandrel was then removed from the center of the tube by handand the tube was cut to the desired length.

Having described the preferred embodiments of the present invention, itis understood that the invention defined by the appended claims is notto be limited by particular details set forth in the above description,as many apparent variations thereof are possible without departing fromthe spirit or scope thereof.

1. A contoured structural member, comprising: at least one contouredinner layer comprising a composite material; at least one contouredouter layer comprising a composite material; at least one intermediatelayer comprising a material with a cellular configuration; and at leastone initiator.
 2. The structural member of claim 1, wherein thestructural member has a closed configuration.
 3. The structural memberof claim 2, further comprising an interior region defined by an innersurface of the at least one inner layer.
 4. The structural member ofclaim 3, wherein the interior region is hollow, partially filled, orcompletely filled.
 5. The structural member of claim 3, wherein the atleast one of the composite materials is formed from a prepreg material.6. The structural member of claim 5, wherein the prepreg materialcomprises a plurality of layers.
 7. The structural member of claim 6,wherein the plurality of layers have a plurality of fibers with anorientation ranging from 0 to about 90 degrees.
 8. The structural memberof claim 1, wherein the structural member has at least one end with theat least one initiator not located near the at least one end.
 9. Thestructural member of claim 8, wherein the at least one initiator islocated from about ½ inch to about 2 inches away from the at least oneend.
 10. The structural member of claim 1, wherein the cellularconfiguration of the at least one intermediate layer comprises a ribbedstructure connecting the at least one inner layer and the art least oneouter layer.
 11. The structural member of claim 10, wherein the ribbedstructure comprises a honeycomb core material.
 12. A contouredstructural member, comprising; at least one contoured inner layercomprising a reinforced resin matrix material; at least one contouredouter layer comprising a reinforced resin matrix material; and at leastone intermediate layer having a geometric cellular configuration; and atleast one initiator.
 13. The structural member of claim 12, wherein thestructural member has at least one end with the at least one initiatorlocated from about ½ inch to about 2 inches away from the at least oneend.
 14. The structural member of claim 13, wherein the at least oneintermediate layer has a ribbed structure connecting the at least oneinner layer and the art least one outer layer.
 15. A contouredstructural member, comprising: at least one contoured inner layercomprising a reinforced resin matrix material; at least one contouredouter layer comprising a reinforced resin matrix material; and at leastone intermediate layer having a ribbed structure connecting the at leastone inner layer and the art least one outer layer; and at least oneinitiator.
 16. The structural member of claims 15, wherein thestructural member has at least one end with the at least one initiatorlocated from about ½ inch to about 2 inches away from the at least oneend.
 17. A contoured structural member having at least one end,comprising: at least one contoured inner layer comprising a reinforcedresin matrix material; at least one contoured outer layer comprising areinforced resin matrix material; and at least one intermediate layerhaving a ribbed structure connecting the at least one inner layer andthe art least one outer layer; and at least one initiator located fromabout ½ inch to about 2 inches away from the at least one end.
 18. Acontoured structural member, comprising: at least one contoured innerlayer comprising a reinforced resin matrix material; at least onecontoured outer layer comprising a reinforced resin matrix material; atleast one intermediate layer having a honeycomb structure connecting theat least one inner layer and the art least one outer layer; and at leastone initiator.
 19. A closed, contoured structural member having at leastone end, comprising: at least one contoured inner layer comprising areinforced resin matrix material; at least one contoured outer layercomprising a reinforced resin matrix material; at least one intermediatelayer having a honeycomb structure connecting the at least one innerlayer and the art least one outer layer; and at least one initiatorlocated from about ½ inch to about 2 inches away from the at least oneend.
 20. A closed, contoured structural member, comprising: at least onecontoured inner layer comprising a reinforced resin matrix material; atleast one contoured outer layer comprising a reinforced resin matrixmaterial; at least one intermediate layer having a honeycomb structurebeing substantially contiguous with the at least one inner layer and theart least one outer layer; and at least one initiator located from about½ inch to about 2 inches away from the at least one end.
 21. A methodfor making a contoured structural member, comprising: providing at leastone inner layer comprising a composite material; roll wrapping at leastone intermediate layer over the at least one inner layer, the at leastone intermediate layer having a cellular configuration; providing atleast one outer layer over the at least one intermediate layer, the atleast one outer layer comprising a composite material; providing atleast one initiator; and connecting the at least one inner and outerlayer to the at least one intermediate layer.
 22. The method of claim21, including providing the at least one inner layer by roll wrappingthe at least one inner layer over a substrate.
 23. The method of claim22, including providing the at least one outer layer by roll wrappingthe at least one outer layer over the at least one intermediate layer.24. The method of claim 23, further including removing the substrate.25. The method of claim 24, including partially or completely fillingthe interior created by removing the substrate.
 26. The method of claim25, further including constraining the at least one outer layer andreacting any reactable material of the at least one inner or outerlayers prior to removing the substrate.
 27. The method of claim 26,including constraining the at least one outer layer by roll wrapping atleast one layer of a shrink-wrap material over the at least one outerlayer.
 28. The method of claim 27, including removing the at least onelayer of the shrink-wrap material after the reaction.
 29. The method ofclaim 27, further including providing at least one pressure distributorover the at least one outer layer.
 30. The method of claim 21, thestructural member having at least one end and further providing the ateast one initiator not located near the at least one end.
 31. A methodfor making a contoured structural member, comprising: roll wrapping atleast one inner layer comprising a reinforced resin matrix material overa substrate; roll wrapping at least one intermediate layer over the atleast one inner layer, the at least one intermediate layer having aribbed structure; and roll wrapping at least one outer layer coveringthe at least one intermediate layer, the at least one outer layercomprising a reinforced resin matrix material; providing at least oneinitiator; connecting the at least one inner and outer layer to the atleast one intermediate layer; and removing the substrate.
 32. A methodfor making a contoured structural member having at least one end,comprising: providing at least one inner layer comprising a compositematerial; roll wrapping at least one intermediate layer over the atleast one inner layer, the at least one intermediate layer having acellular configuration; providing at least one outer layer over the atleast one intermediate layer, the at least one outer layer comprising acomposite material; providing at least one initiator not located nearthe at least one end; and connecting the at least one inner and outerlayer to the at least one intermediate layer.
 33. A contoured structuralmember made by the method comprising: providing at least one inner layercomprising a composite material; roll wrapping at least one intermediatelayer over the at least one inner layer, the at least one intermediatelayer having a cellular configuration; providing at least one outerlayer over the at least one intermediate layer, the at least one outerlayer comprising a composite material; providing at least one initiator;and connecting the at least one inner and outer layer to the at leastone intermediate layer.
 34. A contoured structural member made by themethod comprising: roll wrapping at least one inner layer comprising areinforced resin matrix material over a substrate; roll wrapping atleast one intermediate layer over the at least one inner layer, the atleast one intermediate layer having a ribbed structure; and rollwrapping at least one outer layer covering the at least one intermediatelayer, the at least one outer layer comprising a reinforced resin matrixmaterial; providing at least one initiator; connecting the at least oneinner and outer layer to the at least one intermediate layer; andremoving the substrate.
 35. A contoured structural member having atleast one end made by the method comprising: providing at least oneinner layer comprising a composite material; roll wrapping at least oneintermediate layer over the at least one inner layer, the at least oneintermediate layer having a cellular configuration; providing at leastone outer layer over the at least one intermediate layer, the at leastone outer layer comprising a composite material; providing at least oneinitiator not located near the at least one end; and connecting the atleast one inner and outer layer to the at least one intermediate layer.